“I’ve never been one of these people that has figured out how to roll my clothes and stuff everything into a bag that I carry with me on the plane,” she told Business Insider.

Duffy only spends about a week every month working in Carnival’s Miami headquarters. The rest of the time, she’s travelling around the globe, attending conferences, touring the ships in Carnival’s fleet, and visiting resorts.

Each stop on her trip — like speaking in front of an audience of industry professionals, attending an elegant dinner on deck, and marching through the engine room of a cruise ship — requires starkly different wardrobe choices.

“Going down into the engine room and some of the technical spaces, wearing heels doesn’t work,” she said.

So Duffy always checks a bag and brings along a smaller carry-on containing essentials like her laptop, makeup, and flip flops.

Duffy said her system saves her from a serious bout of pre-journey decision fatigue.

“It just takes too much effort to try to be that efficient and only bring what amounts to a purse and a carry on,” she said. “I don’t have to stress about making all these choices and then being sorry or wishing that I had something that I didn’t pack. You don’t know the weather, what’s going to fit me or feel good that day. I crack up at people when it’s really like a science and they’re only going to bring three pieces and wear them for the week.”